Magnetic stirrer



June 21, 1955 L. LEV] MAGNETIC STIRRER Filed Nov. 23, 1953 'I W M v. y LEONE LEVI y 5 Wg ATTORNEY MAGNETIC STIRRER Leone Levi, New York, N. Y. Application November 23, 1953, Serial No. 393,656

2 Claims. (Cl. 259-122) This invention relates to magnetic stirring devices. It is directed more particularly to magnetic stirring devices wherein the stirrer may be suspended within the body of the liquid, the driving means being mounted overhead.

Mixing of liquids in flasks or closed containers with contemporaneous heating or cooling thereof and with ing the liquid or by employing a stirrer or agitator, or

by passing through the liquid a current of gas or a current of another liquid.

In devices employing the magnetic principle, the stirring generally is eifectuated by the movement of a propeller or a magnetic member lying on the bottom of the container, which propeller is given motion by the rotation of a magnetic field generated outside the container or vessel. Such arrangement makes it difficult directly to heat or cool the base of the container, since such base rests upon, or is closely adjacent, the externally positioned magnetic drive field. Moreover, the motion of the agitator positioned within the liquid produces a shearing effect in that it is directly in contact with the vessel. Furthermore, where the agitating element is positioned in liquid that is corrosive, it is necessary to provide the agitator with a corrosion resistant coating. There has been proposed a magnetic stirring device in which the driving element is positioned overhead and maintained in magnetic contact with a stirrer positioned in the liquid. Such prior proposal, however, involves a complicated, awkward and unwieldy device that cannot easily be assembled and disassembled in carrying out laboratory operations. In pondering over this long standing problem of providing a stirring device based on the magnetic principle which would furnish the advantage of an v rhead drive coupled with simplicity of structure and ready assembly and disassembly, the thought flashed on me that the solution therein might reside in a flask closure adapted to provide primarily a housing for the magnetically actuated driven member of a magnetically coupled stirrer. I found that the concept was operative and provided many of the advantages that had long been sought.

Accordingly, it is among the principal objects of this invention to provide a novel form of magnetic stirrer which is driven by means disposed overhead and characterized by marked simplicity of construction.

A further object of this invention is to provide a novel form of magnetic stirrer which is driven by means disposed overhead and characterized by markedly improved ease of manipulation, and ready mounting and dismountmg.

l t-iterated J A further object of this invention is to provide a flask closure adapted to house the magnetically actuated driven member of a magnetically coupled stirrer.

The foregoing objects as well as other objects and advantages will become more apparent from the following detailed description of the invention taken in conjunction with the accompanying drawing wherein Fig. 1 is a vertical cross section of a magnetic stirrer embodying the principles of this invention mounted in a flask, the flask being shown fragmentarily in phantom.

Fig. 2 is a view, on an enlarged scale, of the upper portion of the embodiment shown in Fig. 1 including the driving element positioned in operative relationship to the driven element.

Fig. 3 is a view of the embodiment illustrated in 2 as seen on the line 33 thereof.

Fig. 4 is a vertical cross section of another form of structure embodying the principles of this invention showing in particular another form of housing for the magnetically actuated driven member of a magnetically coupled stirrer.

Fig. 5 is view of the embodiment illustrated in Fig. 4 as seen on the line 5'5 thereof.

Referring to Figs. 1-3 of the drawing, the numeral 10 designates a mounting member, made of glass or other suitable material, comprising a stopper 12, having an axial bore 14 and an axially aligned tubular stem-like section 16. The stem 16 may be provided with a tubular sidearm 18 for connection with a vacuum line if desired. The stem 16 terminates in an enlarged portion in the form of a housing 2! within which is set the driven magnet 22. The stopper 12 is adapted to be fitted into the neck 24 of a receptacle or flask which contains the material to be stirred. If desired, the stopper may be ground to provide tightness of fit usually associated with a ground-glass stopper.

The driven segment of the stirrer assemblage comprises the driven magnet 22, the stirrer shaft or rod 26 and the agitator 23, the latter being constructed and mounted so as to allow for its passage through stem 16 and bore 14. The upper edge of the driven magnet housing 22 may be a flange-like form as at 32 to provide sufficient surface for the seating thereon of an anti-magnetic or dielectric sealing member 34. Upon this sealing memr ber may be seated the driving magnet 36, carried by driving shaft 38. Sealing member 34- may be a plate or, for example, an inverted crystallizing dish. As shown in Fig. 2, the base of the sealing member 34 may be bowed or dished as at 42. Such configuration minimizes friction between the top and bottom surfaces of the sealing member and the magnets in direct contact therewith. As shown in the drawing, magnets 22 and 36 are made of Alnico cylinders having a plurality of circularly disposed poles as at 44 and 46. The contact of the driving magnet and the driven magnet with the surface of the sealing member takes place only as at the edges 48 and 50.

Referring to Figs. 4 and 5 of the drawing the numeral 16 designates the stem-like portion, akin to 16, which terminates in an enlarged portion in the form of a housing 20 within which is set a driven magnet 22. The driven magnet of the stirrer assemblage (akin to that illustrated in Figs. 1-3) is formed of a magnetic member having a plurality of radially disposed poles 44*. It carries the stirrer rod 9r shaft 26 akin to the rod 26. The sealing member 34' comprises a hollow closure which may be ground-fitted into housing 20 The driving magnet 36 is carried by driving shaft 3%. The poles 46 of driving magnet 36* are disposed so that they are in alignment with the poles 44 of the driven magnet. Upon rotation of the driving magnet, the driven magnet 272 is caused to rotate and the stirrer to perform its agitating action.

it will be obvious that devices embodying the principles of this invention can be mounted in any part of the flask having an appropriate member adapted to receive same. Thus, it is possible not only to position the stirring devices vertically but also diagonally or laterally. The surfaces of the flange 32 may be ground, as in the case of the glass illustrated, and the sealing member seated thereon likewise surfaced so as to provide for sealing of high magnitude.

The stirrer rod or shaft may be inserted into the hole of the magnet and held therein in any suitable manner. A transversely disposed pin positioned at the upper end of the stirrer rod provides a means whereby the rod can be suspended from the upper surface of the driven magnet, or, held in the troughs of adjacent poles of the magnet.

It will be apparent that devices embodying the principles of this invention as above described make it possible to achieve effective sealing of the flask so that it may be heated or cooled as desired; and the contents thereof stirred or agitated effectively. The stirrer may readily be mounted in, and withdrawn from, the flask; and the stirring assemblage itself readily dismantled and reassembled for cleaning, repair, etc.

It will be understood that the foregoing description of the invention and the embodiments shown are merely illustrative of the principles thereof; and, accordingly, that the appended claims are to be construed as defining the invention within the full spirit and scope thereof.

I claim:

1. A device of the class described comprising a stopper having an axially disposed bore, a tubular side arm communicating with said axial bore, an agitator shaft extending through said bore, an agitator carried by said shaft, a magnetic driven member carried by the upper end of said shaft, said driven member being housed Within an enlarged portion of said bore of said stopper, a nonmagnetic sealing member closing the upper end of said stopper, and a magnetic driving member disposed externally of said sealing member.

2. A device of the class described comprising a stopper made as an integral structure; said stopper being tapered at one end so as to be adapted to be inserted in a container opening; a bore extending entirely through the longitudinal axis of the stopper, the bore being enlarged at the end of the stopper which is outside the container; an agitator shaft extending through said bore; an agitator carried by one end of the shaft and adapted to be positioned in the container; a magnetic driven member mounted on the other end of the shaft and positioned in the enlarged portion of the bore; a non-magnetic sealing member closing the end of the stopper in which the enlarged portion of the bore is formed; and a magnetic driving member disposed externally of the sealing member and in magnetic driving relation with the magnetic driven member.

References Cited in the file of this patent UNITED STATES PATENTS 110,504 Simmons et a1. Dec. 27, 1870 1,784,416 Brockmann Dec. 9, 1930 2,283,904 Baumgarden May 26, 1942 2,453,914 Hollenback Nov. 16, 1948 2,469,916 Carter May 10, 1949 2,533,726 Floyd Dec. 12, 1950 2,556,854 Spears et a1 June 12, 1951 2,633,339 Okulitch et al Mar. 31, 1953 2,655,354 Murray Oct. 13, 1953 FOREIGN PATENTS 553,707 France of 1923 

